StructOpt rustc version policy

Contributors can increment minimum rustc version without any justification if the new version is required by the latest version of one of StructOpt's depedencies (cargo update will not fail on StructOpt).

Contributors can increment minimum rustc version if the library user experience is improved.

Why

I use docopt since a long time (pre rust 1.0). I really like the fact that you have a structure with the parsed argument: no need to convert String to f64, no useless unwrap. But on the other hand, I don't like to write by hand the usage string. That's like going back to the golden age of WYSIWYG editors. Field naming is also a bit artificial.

Today, the new standard to read command line arguments in Rust is clap. This library is so feature full! But I think there is one downside: even if you can validate argument and expressing that an argument is required, you still need to transform something looking like a hashmap of string vectors to something useful for your application.

Now, there is stable custom derive. Thus I can add to clap the automatic conversion that I miss. Here is the result.

License

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.